Quick Navigation for Android

I think the navigation bar on Android can be more useful. What will happen if we long press the 'back' button ? :-)
Long press - hold and drag - finger up => quick navigation.

And there are some issues, at first I made the 'back' button stay the left when long pressed because I want the gesture to be coherent. but later I found it that when long pressed, the 'back' button should jump to the right or there is not enough space to drag....that will bring the second tap into the interaction and I don't like it.